After the reported successful launch of the US military MUOS-5 communications satellite into its transfer orbit by a ULA Atlas V launch vehicle, on 24 June, it was revealed to be stranded with its perigee only half way to its planned slightly inclined 36,000 km altitude geostationary orbit.
According to orbit watcher Jonathan McDowell, the satellite is stranded in 35,703 x 15,242 km orbit at 9.8 degrees-inclination. A propulsion system fault preventing its apogee kick motor from working is suspected. The exact cause of the failure has not been revealed however. The BT-4 apogee kick motor is made by IHI Aerospace of Japan is a bipropellant design using hydrazine fuel and nitrogen tetroxide as an oxidiser.
With only US-built low thrust/low efficiency monopropellant thrusters left available to it, hopes are now fading that the satellite can recover itself to its proper operational orbital position given the spacecraft orbit’s perigee shortfall and remaining orbital inclination.
According to the Seradata SpaceTrak database, the value of MUOS 5 is believed to be above US$600 million including construction and launch. The spacecraft is not believed to be insured.
